Antibiotic resistance in microbes is a serious health concern. So researchers have turned their attention to how bacteria undo the action of some antibiotics. Here, scientists set out to find the conditions that help individual bacterial cells survive in the presence of the antibiotic rifampicin. The research team used Mycobacterium smegmatis, a more harmless relative of Mycobacterium tuberculosis, which infects the lung and other organs to cause serious disease.

In this video, genetically identical mycobacteria are growing in a miniature growth chamber called a microfluidic chamber. Using live imaging, the researchers found that individual mycobacteria will respond differently to the antibiotic, depending on the growth stage and other timing factors. The researchers used genetic tagging with green fluorescent protein to distinguish cells that can resist rifampicin and those that cannot. With this gene tag, cells tolerant of the antibiotic light up in green and those that are susceptible in violet, enabling the team to monitor the cells' responses in real time.

To learn more about how the researchers studied antibiotic resistance in mycobacteria, see this news release from Tufts University. Related to image 5751.

Proteins are 3D structures made up of smaller units. DNA is transcribed to RNA, which in turn is translated into amino acids. Amino acids form a protein strand, which has sections of corkscrew-like coils, called alpha helices, and other sections that fold flat, called beta sheets. The protein then goes through complex folding to produce the 3D structure.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool.

Frame 1 shows the two components of the CRISPR system: a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA), and a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence).

In frame 2, the CRISPR machine locates the target DNA sequence once inserted into a cell.

In frame 3, the Cas9 enzyme cuts both strands of the DNA.

Frame 4 shows a repaired DNA strand with new genetic material that researchers can introduce, which the cell automatically incorporates into the gap when it repairs the broken DNA.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video.

Download the individual frames: Frame 1, Frame 2, Frame 3, and Frame 4.

This tropical scene, reminiscent of a postcard from Key West, is actually a petri dish containing an artistic arrangement of genetically engineered bacteria. The image showcases eight of the fluorescent proteins created in the laboratory of the late Roger Y. Tsien, a cell biologist at the University of California, San Diego. Tsien, along with Osamu Shimomura of the Marine Biology Laboratory and Martin Chalfie of Columbia University, share the 2008 Nobel Prize in chemistry for their work on green fluorescent protein-a naturally glowing molecule from jellyfish that has become a powerful tool for studying molecules inside living cells.

DNA (blue) and actin (red) in cultured fibroblast cells.

At the root tips of the mustard plant Arabidopsis thaliana (red), two proteins work together to control the uptake of water and nutrients. When the cell division-promoting protein called Short-root moves from the center of the tip outward, it triggers the production of another protein (green) that confines Short-root to the nutrient-filtering endodermis. The mechanism sheds light on how genes and proteins interact in a model organism and also could inform the engineering of plants.

Human cells with the gene that codes for the protein FIT2 deleted. Green indicates an endoplasmic reticulum (ER) resident protein. The lack of FIT2 affected the structure of the ER and caused the resident protein to cluster in ER membrane aggregates, seen as large, bright-green spots. Red shows where the degradation of cell parts—called autophagy—is taking place, and the nucleus is visible in blue. This image was captured using a confocal microscope.

A fruit fly ovary, shown here, contains as many as 20 eggs. Fruit flies are not merely tiny insects that buzz around overripe fruit--they are a venerable scientific tool. Research on the flies has shed light on many aspects of human biology, including biological rhythms, learning, memory and neurodegenerative diseases. Another reason fruit flies are so useful in a lab (and so successful in fruit bowls) is that they reproduce rapidly. About three generations can be studied in a single month. Related to image 3607.

Genome editing using CRISPR/Cas9 is a rapidly expanding field of scientific research with emerging applications in disease treatment, medical therapeutics and bioenergy, just to name a few. This technology is now being used in laboratories all over the world to enhance our understanding of how living biological systems work, how to improve treatments for genetic diseases and how to develop energy solutions for a better future.

Meiosis is the process whereby a cell reduces its chromosomes from diploid to haploid in creating eggs or sperm. See image 2545 for an unlabeled version of this illustration. See image 2544 for an unlabeled version of this illustration. Featured in The New Genetics.

You are face to face with a 6-day-old zebrafish larva. What look like eyes will become nostrils, and the bulges on either side will become eyes. Scientists use fast-growing, transparent zebrafish to see body shapes form and organs develop over the course of just a few days. Images like this one help researchers understand how gene mutations can lead to facial abnormalities such as cleft lip and palate in people.

This image won a 2016 FASEB BioArt award. In addition, NIH Director Francis Collins featured this on his blog on January 26, 2017.

Flower development is a carefully orchestrated, genetically programmed process that ensures that the male (stamen) and female (pistil) organs form in the right place and at the right time in the flower. In this image of young Arabidopsis flower buds, the gene SUPERMAN (red) is activated at the boundary between the cells destined to form the male and female parts. SUPERMAN activity prevents the central cells, which will ultimately become the female pistil, from activating the gene APETALA3 (green), which induces formation of male flower organs. The goal of this research is to find out how plants maintain cells (called stem cells) that have the potential to develop into any type of cell and how genetic and environmental factors cause stem cells to develop and specialize into different cell types. This work informs future studies in agriculture, medicine and other fields.

This illustration shows pathogenic bacteria behave like a Trojan horse: switching from antibiotic susceptibility to resistance during infection. Salmonella are vulnerable to antibiotics while circulating in the blood (depicted by fire on red blood cell) but are highly resistant when residing within host macrophages. This leads to treatment failure with the emergence of drug-resistant bacteria.

This image was chosen as a winner of the 2016 NIH-funded research image call, and the research was funded in part by NIGMS.

Human metaphase chromosomes are visible with fluorescence in vitro hybridization (FISH). Centromeric alpha satellite DNA (green) are found in the heterochromatin at each centromere. Immunofluorescence with CENP-A (red) shows the centromere-specific histone H3 variant that specifies the kinetochore.

By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, researchers can observe the cells' pulses as green flashes. In response to a stressful environment like one lacking food, B. subtilis activates a large set of genes that help it respond to the hardship. Instead of leaving those genes on as previously thought, researchers discovered that the bacteria flip the genes on and off, increasing the frequency of these pulses with increasing stress. See entry 3254 for the related video.

Genes are often interrupted by stretches of DNA (introns, blue) that do not contain instructions for making a protein. The DNA segments that do contain protein-making instructions are known as exons (green). See image 2551 for a labeled version of this illustration. Featured in The New Genetics.

Like a paint-by-numbers picture, painted probes tint individual human chromosomes by targeting specific DNA sequences. Chromosome 13 is colored green, chromosome 14 is in red and chromosome 15 is painted yellow. The image shows two examples of fused chromosomes—a pair of chromosomes 15 connected head-to-head (yellow dumbbell-shaped structure) and linked chromosomes 13 and 14 (green and red dumbbell). These fused chromosomes—called dicentric chromosomes—may cause fertility problems or other difficulties in people.

A computer-generated sketch of a DNA origami folded into a flower-and-bird structure. See also related image 3690.

Pretty in pink, the enzyme histone deacetylase (HDA6) stands out against a background of blue-tinted DNA in the nucleus of an Arabidopsis plant cell. Here, HDA6 concentrates in the nucleolus (top center), where ribosomal RNA genes reside. The enzyme silences the ribosomal RNA genes from one parent while those from the other parent remain active. This chromosome-specific silencing of ribosomal RNA genes is an unusual phenomenon observed in hybrid plants.

In the worm C. elegans, double-stranded RNA made in neurons can silence matching genes in a variety of cell types through the transport of RNA between cells. The head region of three worms that were genetically modified to express a fluorescent protein were imaged and the images were color-coded based on depth. The worm on the left lacks neuronal double-stranded RNA and thus every cell is fluorescent. In the middle worm, the expression of the fluorescent protein is silenced by neuronal double-stranded RNA and thus most cells are not fluorescent. The worm on the right lacks an enzyme that amplifies RNA for silencing. Surprisingly, the identities of the cells that depend on this enzyme for gene silencing are unpredictable. As a result, worms of identical genotype are nevertheless random mosaics for how the function of gene silencing is carried out. For more, see journal article and press release. Related to image 6532.

Analysis of 68 million-year-old collagen molecule fragments preserved in a T. rex femur confirmed what paleontologists have said for decades: Dinosaurs are close relatives of chickens, ostriches, and to a lesser extent, alligators. A Harvard University research team, including NIGMS-supported postdoctoral research fellow Chris Organ, used sophisticated statistical and computational tools to compare the ancient protein to ones from 21 living species. Because evolutionary processes produce similarities across species, the methods and results may help illuminate other areas of the evolutionary tree. Featured in the May 21, 2008 Biomedical Beat.

Ribonucleic acid (RNA) has a sugar-phosphate backbone and the bases adenine (A), cytosine (C), guanine (G), and uracil (U). Featured in The New Genetics.

See image 2554 for an unlabeled version of this illustration.

New research shows telomeres moving to the outer edge of the nucleus after cell division, suggesting these caps that protect chromosomes also may play a role in organizing DNA.

Xenopus laevis, the African clawed frog, has long been used as a model organism for studying embryonic development. The frog embryo on the left lacks the developmental factor Sizzled. A normal embryo is shown on the right.

The human genome contains much of the information needed for every cell in the body to function. However, different types of cells often need different types of information. Access to DNA is controlled, in part, by how tightly it’s wrapped around proteins called histones to form nucleosomes. The complex shown here, from yeast cells (PDB entry 6Z6P), includes several histone deacetylase (HDAC) enzymes (green and blue) bound to a nucleosome (histone proteins in red; DNA in yellow). The yeast HDAC enzymes are similar to the human enzymes. Two enzymes form a V-shaped clamp (green) that holds the other others, a dimer of the Hda1 enzymes (blue). In this assembly, Hda1 is activated and positioned to remove acetyl groups from histone tails.

Histone proteins loop together with double-stranded DNA to form a structure that resembles beads on a string. See image 2560 for an unlabeled version of this illustration. Featured in The New Genetics.

Hippocampal neuron in culture. Dendrites are green, dendritic spines are red and DNA in cell's nucleus is blue. Image is featured on Biomedical Beat blog post Anesthesia and Brain Cells: A Temporary Disruption?

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue. Here, condensed chromosomes are clearly visible and are starting to separate to form two new cells.

In the absence of the engulfment receptor Draper, salivary gland cells (light blue) persist in the thorax of a developing Drosophila melanogaster pupa. See image 2758 for a cross section of a normal pupa that does express Draper.

This fused chromosome has two functional centromeres, shown as two sets of red and green dots. Centromeres are DNA/protein complexes that are key to splitting the chromosomes evenly during cell division. When dicentric chromosomes like this one are formed in a person, fertility problems or other difficulties may arise. Normal chromosomes carrying a single centromere (one set of red and green dots) are also visible in this image.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video, and download the four images of the CRIPSR illustration here.

HIV is a retrovirus, a type of virus that carries its genetic material not as DNA but as RNA. Long before anyone had heard of HIV, researchers in labs all over the world studied retroviruses, tracing out their life cycle and identifying the key proteins the viruses use to infect cells. When HIV was identified as a retrovirus, these studies gave AIDS researchers an immediate jump-start. The previously identified viral proteins became initial drug targets. See images 2513 and 2515 for other versions of this illustration. Featured in The Structures of Life.

This delicate, birdlike projection is an immature seed of the Arabidopsis plant. The part in blue shows the cell that gives rise to the endosperm, the tissue that nourishes the embryo. The cell is expressing only the maternal copy of a gene called MEDEA. This phenomenon, in which the activity of a gene can depend on the parent that contributed it, is called genetic imprinting. In Arabidopsis, the maternal copy of MEDEA makes a protein that keeps the paternal copy silent and reduces the size of the endosperm. In flowering plants and mammals, this sort of genetic imprinting is thought to be a way for the mother to protect herself by limiting the resources she gives to any one embryo. Featured in the May 16, 2006, issue of Biomedical Beat.

A fruit fly ovary, shown here, contains as many as 20 eggs. Fruit flies are not merely tiny insects that buzz around overripe fruit—they are a venerable scientific tool. Research on the flies has shed light on many aspects of human biology, including biological rhythms, learning, memory, and neurodegenerative diseases. Another reason fruit flies are so useful in a lab (and so successful in fruit bowls) is that they reproduce rapidly. About three generations can be studied in a single month.

Related to image 3656. This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

This image of a mammalian epithelial cell, captured in metaphase, was the winning image in the high- and super-resolution microscopy category of the 2012 GE Healthcare Life Sciences Cell Imaging Competition. The image shows microtubules (red), kinetochores (green) and DNA (blue). The DNA is fixed in the process of being moved along the microtubules that form the structure of the spindle.

The image was taken using the DeltaVision OMX imaging system, affectionately known as the "OMG" microscope, and was displayed on the NBC screen in New York's Times Square during the weekend of April 20-21, 2013. It was also part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Trypanosoma brucei is a single-cell parasite that causes sleeping sickness in humans. Scientists have been studying trypanosomes for some time because of their negative effects on human and also animal health, especially in sub-Saharan Africa. Moreover, because these organisms evolved on a separate path from those of animals and plants more than a billion years ago, researchers study trypanosomes to find out what traits they may harbor that are common to or different from those of other eukaryotes (i.e., those organisms having a nucleus and mitochondria). This image shows the T. brucei cell membrane in red, the DNA in the nucleus and kinetoplast (a structure unique to protozoans, including trypanosomes, which contains mitochondrial DNA) in blue and nuclear pore complexes (which allow molecules to pass into or out of the nucleus) in green. Scientists have found that the trypanosome nuclear pore complex has a unique mechanism by which it attaches to the nuclear envelope. In addition, the trypanosome nuclear pore complex differs from those of other eukaryotes because its components have a near-complete symmetry, and it lacks almost all of the proteins that in other eukaryotes studied so far are required to assemble the pore.

HIV is a retrovirus, a type of virus that carries its genetic material not as DNA but as RNA. Long before anyone had heard of HIV, researchers in labs all over the world studied retroviruses, tracing out their life cycle and identifying the key proteins the viruses use to infect cells. When HIV was identified as a retrovirus, these studies gave AIDS researchers an immediate jump-start. The previously identified viral proteins became initial drug targets. See images 2514 and 2515 for labeled versions of this illustration. Featured in The Structures of Life.

This is a magnified view of an Arabidopsis thaliana leaf after several days of infection with the pathogen Hyaloperonospora arabidopsidis. The pathogen's blue hyphae grow throughout the leaf. On the leaf's edges, stalk-like structures called sporangiophores are beginning to mature and will release the pathogen's spores. Inside the leaf, the large, deep blue spots are structures called oopsorangia, also full of spores. Compare this response to that shown in Image 2781. Jeff Dangl has been funded by NIGMS to study the interactions between pathogens and hosts that allow or suppress infection.

The structure of a gene-regulating zinc finger protein bound to DNA.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue.

Related to images 1010, 1011, 1013, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.

To splice a human gene (in this case, the one for insulin) into a plasmid, scientists take the plasmid out of an E. coli bacterium, cut the plasmid with a restriction enzyme, and splice in insulin-making human DNA. The resulting hybrid plasmid can be inserted into another E. coli bacterium, where it multiplies along with the bacterium. There, it can produce large quantities of insulin. See image 2564 for an unlabeled version of this illustration. Featured in The New Genetics.

Yeast make bread, beer, and wine. And like us, yeast can reproduce sexually. A mother and father cell fuse and create one large cell that contains four offspring. When environmental conditions are favorable, the offspring are released, as shown here. Yeast are also a popular study subject for scientists. Research on yeast has yielded vast knowledge about basic cellular and molecular biology as well as about myriad human diseases, including colon cancer and various metabolic disorders.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool. This is the fifthframe in a series of five. The CRISPR system has two components joined together: a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence) and a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA). For an explanation and overview of the CRISPR-Cas9 system, see the NIGMS Biomedical Beat blog entry, Field Focus: Precision Gene Editing with CRISPR and the iBiology video, Genome Engineering with CRISPR-Cas9: Birth of a Breakthrough Technology.

Duplicated pair of chromosomes have exchanged material.

An atomic force microscopy image shows DNA folded into an intricate, computer-designed structure. The image is featured on Biomedical Beat blog post Cool Images: A Holiday-Themed Collection. For more background on DNA origami, see Cool Image: DNA Origami. See also related image 3690.

Haplotypes are combinations of gene variants that are likely to be inherited together within the same chromosomal region. In this example, an original haplotype (top) evolved over time to create three newer haplotypes that each differ by a few nucleotides (red). See image 2567 for a labeled version of this illustration. Featured in The New Genetics.

These images show three stages of cell division in Xenopus XL177 cells, which are derived from tadpole epithelial cells. They are (from top): metaphase, anaphase and telophase. The microtubules are green and the chromosomes are blue. Related to 3443.

Los ritmos circadianos son cambios físicos, mentales y conductuales que siguen un ciclo de 24 horas. Los ritmos circadianos típicos conducen a un nivel alto de energía durante la mitad del día (de 10 a.m. a 1 p.m.) y un bajón por la tarde. De noche, los ritmos circadianos hacen que la hormona melatonina aumente, lo que hace que la persona se sienta somnolienta.

Vea 6611 para la versión en inglés de esta infografía.

The microtubule severing protein, katanin, localizes to chromosomes and regulates anaphase A in mitosis. The movement of chromosomes on the mitotic spindle requires the depolymerization of microtubule ends. The figure shows the mitotic localization of the microtubule severing protein katanin (green) relative to spindle microtubules (red) and kinetochores/chromosomes (blue). Katanin targets to chromosomes during both metaphase (top) and anaphase (bottom) and is responsible for inducing the depolymerization of attached microtubule plus-ends. This image was a finalist in the 2008 Drosophila Image Award.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue.

Related to images 1010, 1011, 1012, 1014, 1015, 1016, 1017, 1018, 1019, and 1021.